Modern lifestyle is undergoing fundamental changes due to a quick emergence of a mobile computing paradigm. According to market statistics and forecasts, smartphones and tablets outsold personal computers for the first time in the fourth quarter of 2011. In the fourth quarter of 2014, unit shipment volumes of tablets alone have exceeded cumulative personal and business PC shipments. Some analytic reports predict that by 2016 there will be over ten billion Internet-connected mobile devices in the hands of end users, of which approximately eight billion will be smartphones and tablets; and by 2017, about 87% of the market share of smart connected devices is expected to belong to smartphones and tablets compared with 13% for desktop and mobile PCs.
In response to growing volumes and expanding feature sets of smartphones and tablets, a new generation of mobile software applications has emerged. These software applications utilize enhanced connectivity of mobile devices and take advantage of content capturing capabilities enabled by embedded cameras, microphones, handwritten input in mobile devices; the applications also make use of device motion sensors, multi-touch screens, etc.
One of the smartphone application categories is related to use of phone cameras. According to industry statistics, well over 80% of mobile phones and nearly all smartphones are shipping with a quality camera, stimulating a quick growth of mobile scanning applications, which are already used by hundreds of millions people worldwide. This new content capturing paradigm increasingly includes taking, storing and processing photographs of paper documents. According to recent market surveys, a smartphone or a tablet camera for document capture combined with cloud file services for document storage and retrieval are used by more smartphone and tablet users than earlier solutions with mobile scanners and mobile printing services.
Online services and multi-platform software such as the Evernote service and platform by the Evernote Corporation of Redwood City, Calif., ABBYY by the ABBYY Group of Companies, the Dropbox service by Dropbox, Inc., and many other solutions offer image storing and advanced processing, as well as keyword and other types of searching within images of photographed documents.
Notwithstanding significant advances in smartphone camera quality, processing power of mobile devices, and increased capabilities and features of online services, including extensive document and image processing features, the process of high quality scanning of documents using smartphone and tablet cameras still faces significant challenges. Obtaining quality images of typed, handwritten and combined pages using a camera phone may present a difficult task for a variety of reasons; thus, photographs of handwritten and printed pages may be subject to variable lighting conditions, to perspective distortion and to background effects depending on the surface a document may be residing on; pages may be bent toward notebook edges or a dividing line creating an arc-shaped page, etc.
Techniques for correcting real-life photo images with shadows, reflections and various types of distortions have been explored by many vendors with varying degrees of success. One of the most challenging tasks of image capturing via mobile cameras is glare mitigation. In contrast with conventional paper scanners that provide stable and optimal lighting conditions for captured documents, the scanning process for paper documents with phone cameras may be subject to variable lighting conditions, as well as to adaptation requirements related to different types of paper, texturing of page surface, specific parameters of printed or handwritten text and drawings, including reflective characteristics of ink and typographic paint, etc.
In particular, the presence of external sources of light, as well as usage of a smartphone's own light source, independently or in combination with a camera flash, may cause persistent and stable or temporary and random reflections from the paper surface and may create one or multiple glare spots on a captured image of a paper document. Subsequently, portions of typed or handwritten content of the document (text, charts, drawings, etc.) may be obstructed on a captured image, preventing the digital content from viewing, editing, search and other types of processing.
Accordingly, it is desirable to provide glare mitigation in connection with capturing photographs of paper and other conventional documents using smartphone cameras.